KICKDOWN ADJUSTEMENTS on TORQUEFLITE "cast iron"

Since i overhauled some Torqueflites i always had some problems with the "forced kickdown" (or forced downshift 3-2 or 2-1 or 3-1). Generally it does not function properly and one depresses in vain on the accelerator, the car does not downshift..

VERY SIGNIFICANT: on all the "old transmissions"  (before '70) the kickdown occurs only in the last 1/10 inches before the pedal goes to floor. If you accelerate hardly but without going "to the floor" you will not have a kickdown !

For a few weeks I have studied well the question, send requests to the mailing lists and made various tests.

 Now I have a  correct kickdown on my Imperial !! It's just a matter of adjustment but NOT AS INDICATES IN the SHOP MANUAL . Only problem, as my transmission upshifts badly  from 2 into 3 (lack of synchronization between release of  KD band and engagement of rear clutch) I have it also in kickdown 3-2. Thus my trans. should re-overhauled this winter. But at least it "(forced) downshifts" now !  Problem solved (at 90 %) : bad kickdown band adjustement (with manual adjustement...), i'll let know what happen on mailing list.

The various methods of the FSM are  described on the pics A-B-C-D-E  below (click to enlarge). Approximately, here what is indicated (I summarize):

  • check if the accelerator pedal has a 118  angle  to horizontal (or 115 or 114, that depends on the model or FSM)
  •  Run engine until normal temperature is reached then stop. Check for choke being fully opened . Set idle to 500 rpm.
  • Loosen the carburetor throttle linkage nut on the carb. rod ("B" on left pic)
  • Move the rod rearward against idle stop (in trans.).
  • With rod preloaded and in line, lock the adjusting nut

But this method doesn't work on my car ! If i make the FSM adjustement the transmission throttle lever can't go to "kickdown" position (all the way backwards) when the accelrator pedal is floored..

I advise you to first test the FSM method and if it doesn't work (lack of KD), take a look at my method (bottom of this page)

A B C D E
'57-58-59 adjustements (shop manual) another '59 adjustement 300C throttle linkage adjust.

 


brief technical pics and checks on a disassembled valve body : various positions of the "throttle lever" according to the kickdown valve position

Note: on all pics o this page the "throttle valve spring" has been removed for purpose of easier pics. This spring is between kickdown and throttle valves , see position on pic # 1 and pic 4c.

Picture 1 : "release" position (throttle lever on "stop" adjusting bolt). The port A is closed by k.d valve large diameter. You can seen a part of this large diameter at the left of A . The "check balls port"  has been tracked on the other valve bodies and yes it leads to check balls "1-2" and "2-3" which are in the lower valve body then to shift valves.
According to the pic, this check balls port is in relation with the "vent" port via spring and small diameter k.d. valve

Click to enlarge

1 1a 1b  
Valve position 3/4(refer to pic at extreme right to know how i take mesaurement) How i measure at throttle lever: between front of cable housing (at cable opening)  and larger diameter of the throttle lever

 


Picture 2 :  As it is with light throttle (1/4 maybe ?). The throttle lever has pushed a little the k.d valve. Port A remains closed

 

2 2a 2b
Valve position    2  9/16 "

 


Picture 3 : You push hard on the gas pedal so throttle lever pushes on k.d valve stem (you feel resistance because you must compress the valve spring). But the port A is always closed (the larger diameter hasn't still open the port, see pic) ... So no kickdown

 

3 3a 3b

Valve position

3 1/4 "

 


Picture 4 : maximum travel of throttle lever , the k.d valve is all the way in and the valve spring is completly compressed (need a lot of strenght..). Now the port A is open and throttle pressure can go to the check balls and 1-2 / 2-3 shift valves. The "larger diameter" k.d valve closes now the opening between "check balls port" and vent port.

this is the kickdown position

4 4a 4b
Valve position   9/16 "
     
4d

4c

complete description and schematic at Torqueflite "cast iron" page

 

How i adjust :

  • Check , with pedal floored, that the butterflies of the carb  are fully opened and that the carb linkage is bottomed (all the way forward) . You can shorten a little the accelerator pedal rod from under the car. It's a very important step because if ther's something who prevents the pedal to be floored (i.e carpet or mat) you'll never go to KD . 118 or 115 , don't worry, you must have a complete travel before floor.
  • At trans., remove the "accelerator shatft to transmission rod assy" (cotterpin) , see pic at top of the page, and check the measurements given in pics # 1b and 4b (extreme positions).  Normally you'll find the same than mine . Anyway ther's no adjustement...
  • Move the throttle lever against its rear stop (KD position as in pic 4b) , have an help who floors the accelerator pedal and check if the cotterpin shaft of the rod is in line with the throttle lever mounting hole. Best is to have the rod a fraction of inch further from the throttle hole.
  • If adjustement is to be made, shorten (rarely..) or lenghten the rod at locknut "A" or"A" on pic below. Yes, the manual says: the purpose of this adjustement is to allow for variations between chassis and engine assemblies (..) and should not be used for making throttle linkage adjustement. But in my case it was the only adjustement which works !  Check again the adjustement and tell to your help in car to release and floor several times the pedal. When the pedal is 95 to 100 % floored, the throttle lever must be all the way rearward. 
    After this adjustement, if the pedal is released you'll see that the throttle lever doesn't bottomed on "idle" stop (like 1b pic) but rather at an intermediate position between 1b and 2b So if you follow the FSM manual with throttle lever on "idle stop" you never go to KD position.

Now test the car ..

 

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